Horton

Re: cataloguing NOT NULL constraints

Dean Rasheed <dean.a.rasheed@gmail.com>

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From: Dean Rasheed <dean.a.rasheed@gmail.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Peter Eisentraut <peter@eisentraut.org>, pgsql-hackers@lists.postgresql.org
Date: 2023-07-13T13:56:44Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Revert structural changes to not-null constraints

  2. Fix inconsistencies in error messages

  3. Disallow direct change of NO INHERIT of not-null constraints

  4. Disallow NO INHERIT not-null constraints on partitioned tables

  5. Better handle indirect constraint drops

  6. Don't try to assign smart names to constraints

  7. Fix restore of not-null constraints with inheritance

  8. ATTACH PARTITION: Don't match a PK with a UNIQUE constraint

  9. Fix propagating attnotnull in multiple inheritance

  10. Check stack depth in new recursive functions

  11. Move privilege check to the right place

  12. Update information_schema definition for not-null constraints

  13. Fix not-null constraint test

  14. Disallow changing NO INHERIT status of a not-null constraint

  15. Catalog not-null constraints

  16. parallel_schedule: add comment on event_trigger test dependency

  17. Revert "Catalog NOT NULL constraints" and fallout

  18. Adjust contrib/sepgsql regression test expected outputs.

  19. Fix table name clash in recently introduced test

  20. Catalog NOT NULL constraints

  21. Change the rules for inherited CHECK constraints to be essentially the same

On Wed, 12 Jul 2023 at 18:11, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> v13, because a conflict was just committed to alter_table.sql.
>
> Here I also call out the relcache.c change by making it a separate
> commit.  I'm likely to commit it that way, too.  To recap: the change is
> to have a partitioned table's index list include the primary key, even
> when said primary key is marked invalid.  This turns out to be necessary
> for the currently proposed pg_dump strategy to work; if this is not in
> place, attaching the per-partition PK indexes to the parent index fails
> because it sees that the columns are not marked NOT NULL.
>

Hmm, looking at that change, it looks a little ugly. I think someone
reading that code in the future will have no idea why it's including
some invalid indexes, and not others.

> There are no other changes from v12.  One thing I should probably get
> to, is fixing the constraint name comparison code in pg_dump.  Right now
> it's a bit dumb and will get in silly trouble with overlength
> table/column names (nothing that would actually break, just that it will
> emit constraint names when there's no need to.)
>

Yeah, that seems a bit ugly. Presumably, also, if something like a
column rename happens, the constraint name will no longer match.

I see that it's already been discussed, but I don't like the fact that
there is no way to get hold of the new constraint names in psql. I
think for the purposes of dropping named constraints, and also
possible future stuff like NOT VALID / DEFERRABLE constraints, having
some way to get their names will be important.

Something else I noticed is that the result from "ALTER TABLE ...
ALTER COLUMN ... DROP NOT NULL" is no longer easily predictable -- if
there are multiple NOT NULL constraints on the column, it just drops
one (chosen at random?) and leaves the others. I think that it should
either drop all the constraints, or throw an error. Either way, I
would expect that if DROP NOT NULL succeeds, the result is that the
column is nullable.

Regards,
Dean